Reconstituted surfactants having improved properties

ABSTRACT

Reconstituted surfactants comprising a lipid carrier, a polypeptide analog of the native surfactant protein SP-C, and a polypeptide analog of the native surfactant protein SP-B are useful for the treatment and/or prophylaxis of RDS and other respiratory disorders.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/422,581, filed on Apr. 13, 2009, now U.S. Pat. No. 8,183,210, whichwas a continuation of International Patent Application No.PCT/IB2007/002841, filed on Sep. 28, 2007, and claims priority toEuropean Patent Application No. 06021521.7, filed on Oct. 13, 2006, bothof which are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reconstituted surfactants which areuseful for the treatment or prophylaxis of RDS and other respiratorydisorders. The present invention also relates to methods of preparingsuch a reconstituted surfactant and pharmaceutical compositions whichcontain such a reconstituted surfactant. The present invention furtherrelates to methods for the treatment or prophylaxis of RDS and otherrespiratory disorders by administering such a reconstituted surfactant.

2. Discussion of the Background

The human lung is composed of a large number of small air sacs, calledalveoli, in which gases are exchanged between the blood and the airspaces of the lungs. In healthy individuals, this exchange is mediatedby the presence of a protein-containing surfactant complex that preventsthe lungs from collapsing at the end of expiration.

Lung surfactant complex is composed primarily of lipid and containsminor amounts of various proteins. An absence of adequate levels of thiscomplex results in malfunction of the lung. This syndrome is calledRespiratory Distress Syndrome (RDS) and it commonly affects preterminfants.

Said syndrome is effectively treated with modified natural surfactantpreparations extracted from animal lungs. Commercially availablemodified surfactant preparations are, for example, Curosurf, derivedfrom porcine lung, Infasurf, extracted form calf lung lavage, andSurvanta, a chemically modified natural bovine lung extract.

The main constituents of these surfactant preparations arephospholipids, such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholinecommonly known as dipalmitoylphosphatidylcholine (DPPC),phosphatidylglycerol (PG), and surfactant hydrophobic proteins B and C(SP-B and SP-C).

Due to the drawbacks of the surfactant preparations from animal tissues,such as the complication of the production and sterilization processesand possible induction of immune reactions, synthetic surfactantsmimicking the composition of the modified natural surfactants have beendeveloped. Said synthetic surfactants are known as reconstitutedsurfactants. However the development of clinically active reconstitutedsurfactants has turned out to be complicated since the nativehydrophobic proteins are too big to synthesize, structurally complex,and unstable in pure form.

In order to replace said native hydrophobic proteins, some syntheticpolypeptides partially corresponding to their sequences and analogsthereof have been proposed in the prior art and are disclosed in forexample WO 89/06657, WO 92/22315, WO 98/49191, WO 95/32992, U.S. Pat.No. 6,660,833, EP 413,957, and WO 91/18015.

WO 00/47623 disclosed synthetic polypeptides which are analogs of thenative protein SP-C wherein: i) cysteine residues in position 5 and 6have been replaced by Ser residues; ii) the Val residues of the ‘centerregion’ of SP-C have been substituted with other neutral and hydrophobicresidues selected from the group consisting of Leu, Ile, and norleucine(nL); iii) some of the neutral amino acids present in the ‘centerregion’ of SP-C have been replaced with bulky or polar residues selectedfrom the group consisting of Lys, Trp, Phe, Tyr, and Ornithine. Saidartificial polypeptides are characterized by the fact that they arecapable of folding like the native protein SP-C and, hence, interactingproperly with the surfactant lipids and, thus, do not give rise toself-oligomerization.

WO 00/76535 generically discloses pulmonary surfactant preparationscomprising at least one modification of the SP-B in combination with atleast one modification of the SP-C protein.

In A. J. Waring, et al., (abstract presented at the Paediatric AcademySociety Annual meeting held in San Francisco on Apr. 29-May 2, 2006) astudy was undertaken to examine the activity of a synthetic surfactantconstituted of the SP-C-mimic, SP-Cff, that is a synthetic 34-residueSP-C with phenylalanine instead of cysteine in positions 4 and 5, andthe SP-B-mimic, Mini-B.

However, according to the available literature, in animal studies, thetreatment with reconstituted surfactants gives rise to poor lung gasvolumes and grade of alveolar patency at the end of expiration, and aventilation is required with a positive end expiratory pressure (PEEP)in order to achieve an in vivo activity comparable to that achieved withmodified natural surfactants (see, J. Johansson, et al., J. Appl.Physiol., 2003, 95, 2055-2063; and A. J. Davis, et al., Am. J. Respir.Crit. Care Med., 1998; 157, 553-559). Thus, the available reconstitutedsurfactant preparations are indeed not capable of forming a stablephospholipidic film in the alveoli at the end of expiration.

Moreover, all of the aforementioned documents are silent about theproblem of the alveolar patency at the end of expiration and the effectof the disclosed preparations thereof.

Thus, there remains a need for a reconstituted surfactant with improvedproperties in terms of lung compliance.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide novelreconstituted surfactants which are useful for the treatment orprophylaxis of RDS and other respiratory disorders.

It is another object of the present invention to provide novelreconstituted surfactants which are capable of guaranteeing alveolarstability, and hence maintaining alveolar patency at the end ofexpiration without requiring ventilation with PEEP.

It is another object of the present invention to provide novel methodsof preparing such a reconstituted surfactant.

It is another object of the present invention to provide novelpharmaceutical compositions which contain such a reconstitutedsurfactant.

It is another object of the present invention to provide novel methodsof treating and/or preventing RDS and other respiratory disorders byadministering such a reconstituted surfactant.

These and other objects, which will become apparent during the followingdetailed description, have been achieved by the inventors' discoverythat particular analogues of the native SP-C protein, and preferably thepolypeptides of WO 00/47623 can advantageously be combined withparticular analogues of the native protein SP-B in order to provide areconstituted surfactant preparation with improved properties in termsof lung compliance, and in particular the ability to efficaciouslymaintain alveolar patency at the end of expiration without requiringventilation with PEEP.

Thus, in a first embodiment, the present invention provides areconstituted surfactant comprising a lipid carrier, and a combinationof a particular polypeptide analog of the native surfactant protein SP-Cwith a particular polypeptide analog of the native surfactant proteinSP-B.

In particular the invention provides a reconstituted surfactantcomprising:

-   -   a) a lipid carrier;    -   b) a polypeptide of at least 20 amino acid residues and no more        than 40 amino acid residues having the sequence represented by        the general formula (I) (SEQ ID NO: 10):        F_(e)G_(e)I_(f)P_(f)S_(g)SPVHLKRX_(a)BX_(b)(BX_(c))_(n)GALL_(n)Ω_(p)G_(p)L_(p)  (I)        wherein:    -   each X is independently an amino acid residue selected from the        group consisting of I, L, and nL;    -   each B is independently an amino acid residue selected from the        group consisting of K, R, H, W, F, Y, and Orn;    -   each S is independently optionally substituted with an acyl        group containing 12-22 carbon atoms, preferably 16 carbon atoms,        linked to the side chain via an ester bond;    -   Ω is an amino acid selected from the group consisting of M or M        oxidized on the sulfur atom, I, L, and nL;    -   a is an integer having a value of 1 to 8;    -   b is an integer having a value of 1 to 19;    -   each c is independently an integer having a value of 3 to 8;    -   e, f, g, and p are each independently integers having a value of        0 or 1;    -   each n is independently an integer having a value of 0 to 3; and        with the condition that the X_(a)BX_(b)(BX_(c))_(n) is a        sequence having a maximum of 22 amino acid residues; and    -   c) a polypeptide represented by the general formula (II) (SEQ ID        NO: 11):        C_(f)ΔLCRALIKRIQAΩIPKGGRΩLPQLVCRLVLΦCS_(f)  (II)        wherein:    -   Δ is an amino acid residue independently selected from the group        consisting of W and L;    -   each Ω is independently an amino acid residue selected from the        group consisting of M, I, L, and nL;    -   Φ is an amino acid residue independently selected from the group        consisting of R and T, preferably R; and    -   each f is independently an integer having a value of 0 or 1,    -   wherein F, G, I, P, S, V, H, L, K, R, A, C, Q, W, Y, M, and T        are standard one-letter symbols for amino acid residues, nL        represents an L-nor-leucine residue, and Orn represents an        L-onithine residue.

The present invention also provides pharmaceutically acceptable salts ofsaid polypeptides and their blocked N- and/or C-terminus derivatives,e.g via acetylation and amidation.

The present invention also provides pharmaceutical compositions whichcontain such a reconstituted surfactant.

The present invention also provides methods for improving the alveolarpatency at the end of expiration by administering such a reconstitutedsurfactant.

The present invention also provides methods for the prophylaxis and/ortreatment of respiratory distress syndrome (RDS) and other respiratorydisorders, by administering to a patient in need of such treatment atherapeutically effective amount of a reconstituted surfactantcomprising a lipid carrier, a polypeptide of general formula (I), and apolypeptide of general formula (II).

In particular it has been found that, in a model of RDS wherein theimmature newborn were treated with exogenous surfactant preparationswithout applying PEEP, a combination of said particular analogues of theproteins SP-C and SP-B acts on the lung gas volumes which is an index ofthe alveolar patency at the end of expiration.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same become betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows the sequence of human protein SP-C. The Cys residues arepalmitoylated in native SP-C. FIG. 1 discloses SEQ ID NO: 17.

FIG. 2 shows the sequence of human protein SP-B. FIG. 2 discloses SEQ IDNO: 18.

FIG. 3 shows certain results in terms of lung gas volumes (ml/kg).

FIG. 4 shows certain results in terms of tidal volumes (ml/kg) as afunction of time/pressure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The respiratory function after in vivo treatment with the exogenoussurfactant preparations is carried out by measuring two parameters:

i) the tidal volume which is an index of the lung compliance and

ii) the lung gas volume which is an index of the alveolar air expansionor patency at the end of expiration, and, hence, of the capability offorming a stable phospholipidic film in the alveoli at the end ofexpiration.

In the present application, the term “reconstituted surfactant” means alipid carrier to which polypeptide analogues of the surfactant proteins,made through recombinant technology or synthetic methods, have beenadded.

The term “lipid carrier” means a mixture of phosholipids and optionallyfurther lipid components, for example neutral lipids such astriacylglycerols, free fatty acids, and/or cholesterol.

The term “polypeptide analogues of the native surfactant protein SP-C”,includes polypeptides having an amino acid sequence in which, comparedto the native proteins, one or more amino acids are missing or have beenreplaced by other amino acids, so long as the polypeptides, in a mixturewith a lipid carrier, show pulmonary surfactant activity.

The term “polypeptide analogues of the native surfactant protein SP-B”,includes peptides having an amino acid sequence in which, compared tothe native proteins, one or more amino acids are missing so long as thepolypeptides, in a mixture with a lipid carrier, show pulmonarysurfactant activity.

The term “mini-B” means a 34-residue polypeptide based on the N-terminalresidues 8-25 and C-terminal residues 63-78 of the native SP-B proteinwhose structure was first generically disclosed in a presentation takenfrom the California NanoSystems Institute website. Its full sequence hasbeen subsequently disclosed in the RCSB Protein Data Bank. In A. J.Waring, et al., J. Peptide Res., 2005, 66, 364-374, more informationabout its structure and activity has been reported.

The term “variants” means polypeptide analogues of the Mini-B peptidehaving an amino acid sequence in which one or more amino acids have beenreplaced by other amino acids, so long as the peptides, in a mixturewith a lipid carrier, retain the activity of Mini-B.

The amino acid sequences are shown according to the single-letter orthree-letter code with the amino acid which carries the free amino groupat the left end (amino terminus) and the amino acid which carries thefree carboxyl group at the right end (carboxy terminus).

The term “synergistic” means that the effectiveness of the twopolypeptides is more than would be expected by summing their respectiveindividual effectiveness in a given assay.

All the amino acid residues identified herein are in the naturalL-configuration and the sequences identified herein are reportedaccording to standard abbreviations for amino acid residues as shown inthe following Table of Correspondence.

Table of Correspondence

Symbol Amino Acid One Letter Three Letter Glycine G Gly L-proline P ProL-isoleucine I Ile L-leucine L Leu L-tyrosine Y Tyr L-cysteine C CysL-tryptophan W Trp L-alanine A Ala L-lysine K Lys L-arginine R ArgL-glutamine Q Glu L-methionine M Met L-serine S Ser L-valine V ValL-aspargine N Asn L-aspartic acid D Asp L-glutamic acid E GlnL-histidine H His L-threonine T Thr L-phenylalanine F Phe L-nor-leucine— nLeu L-omithine — Orn

Thus, the present invention provides reconstituted surfactantscomprising a lipid carrier and a combination of particular polypeptideanalogues of the native surfactant protein SP-C with particularpolypeptide analogues of the native surfactant protein SP-B, includingthe Mini-B peptide and variants thereof.

It has been found that, in a model of RDS wherein the immature newbornwere treated with exogenous surfactant preparations without applyingPEEP, a combination of a polypeptide of general formula (I), with apolypeptide of general formula (II) positively acts on the lungcompliance. In particular, the combination of the two polypeptides wasfound to act in a synergistic way on the lung gas volumes which is anindex of the alveolar patency at the end of expiration. Said resultdemonstrates that the reconstituted surfactant of the present inventionis able to stabilise the phospholipid film in the alveoli at the end ofexpiration in a better way than a reconstituted surfactant comprisingonly an analog of the protein SP-C or an analog of the protein SP-B.

Moreover, the claimed reconstituted surfactant preparation also improvedthe respiratory function as expressed by the tidal volumes to an extentcomparable or even slightly better than that achieved afteradministration of a modified natural surfactant.

Advantageously the analog of the native protein SP-C is a polypeptide ofat least 20 amino acid residues and no more than 40 amino acid residues,having the sequence represented by the general formula (I) SEQ ID NO:10:F_(e)G_(e)I_(f)P_(f)S_(g)SPVHLKRX_(a)BX_(b)(BX_(c))_(n)GALLΩ_(p)G_(p)L_(p)  (I)wherein:

-   -   each X is independently an amino acid residue selected from the        group consisting of I, L, and nL;    -   each B is independently an amino acid residue selected from the        group consisting of K, R, H, W, F, Y, and Orn;    -   each S is independently optionally substituted with an acyl        group containing 12-22 carbon atoms, preferably 16 carbon atoms,        linked to the side chain via an ester bond;    -   Ω is an amino acid residue selected from the group consisting of        M or its oxidized on the sulfur atom, I, L, and nL;    -   a is an integer having a value of 1 to 8;    -   b is an integer having a value of 1 to 19;    -   each c is independently an integer having a value of 3 to 8;    -   e, f, g and p are each independently integers having a value of        0 or 1;    -   n is an integer having a value comprised from 0 to 3; and    -   with the condition that the X_(a)BX_(b)(BX_(c))_(n) is a        sequence having a maximum of 22 amino acids, preferably        comprised between 10 and 22 amino acid residues.

Preferably the polypeptide of general formula (I) is constituted of atleast 30 and not more than 35 amino acid residues, more preferably notmore than 33 amino acid residues.

In particular embodiments, the polypeptides of general formula (I) areconstituted of 30 or 33 or 35 amino acid residues.

Preferably the polypeptide analog of the SP-C protein is represented bythe general formula (Ia) (SEQ ID NO: 13) in which e and n are 0, and gis 1:I_(f)P_(f)SSPVHLKRX_(a)BX_(b)GALLΩ_(p)G_(p)L_(p)  (Ia)wherein

-   -   X, B, and Ω are as defined above;    -   a is from 1 to 8, preferably from 1 to 3; more preferably 1;    -   b is from 1 to 19, preferably from 5 to 15; more preferably 14;        and    -   each f and p are independently 0 or 1.

More preferably the polypeptide analog of the SP-C protein isrepresented by the general formula (Ib) (SEQ ID NO: 14) in which f is 1:IPSSPVHLKRX_(a)BX_(b)GALLΩ_(p)G_(p)L_(p)  (Ib)wherein:

-   -   X, B, Ω, a, and b are as defined above; and    -   each p is independently 0 or 1.

Even more preferably, the polypeptide analog of the SP-C protein isrepresented by the general formula (Ic) (SEQ ID NO: 15):IPSSPVHLKRLKLLLLLLLLILLLILGALLΩ_(p)G_(p)L_(p)  (Ic)wherein:

-   -   Ω is as defined above    -   each p is independently 0 or 1.

Examples of polypeptides of formula (Ic) are reported below:

(SEQ ID NO: 1) IPSSPVHLKRLKLLLLLLLLILLLILGALLMGL (Id) (SEQ ID NO: 2)IPSSPVHLKRLKLLLLLLLLILLLILGALLIGL (Ie) (SEQ ID NO: 3)IPSSPVHLKRLKLLLLLLLLILLLILGALLLGL (If) (SEQ ID NO: 4)IPSSPVHLKRLKLLLLLLLLILLLILGALLnLGL (Ig)  (SEQ ID NO: 5)IPSSPVHLKRLKLLLLLLLLILLLILGALL (Ih).

The polypeptide (Id) has been also referred to in the prior art asSP-C33.

Most preferably the SP-C analog is a polypeptide selected from the groupof polypeptides having the formulae (Ie), (If), (Ig), and (Ih).

In a preferred embodiment of the invention, the polypeptide of generalformula (I) is the polypeptide (If) hereinafter referred to asSP-C33(Leu)³¹.

Advantageously, the analog of the native protein SP-B consists of twoportions corresponding to the N-terminal residues 8-25 and to the 63-78C-terminal part of the native SP-B protein (referred to as Mini-Bpeptide) or a variant thereof.

More advantageously, the analog of the native protein SP-B is apolypeptide represented by the following general formula (II) (SEQ IDNO: 11):C_(f)ΔLCRALIKRIQAΩIPKGGRΩLPQLVCRLVLΦCS_(f)  (II)wherein:

-   -   Δ is an amino acid residue selected form the group consisting of        W and L;    -   each Ω is independently an amino acid residue independently        selected from the group consisting of M, I, L, and nL;    -   Φ is an amino acid residue selected from the group consisting of        R and T, preferably R; and    -   each f is independently an integer having a value of 0 or 1.

In a particular embodiment of the invention, the SP-B analog is apolypeptide represented by the formula (IIa) (SEQ ID NO: 6):CWLCRALIKRIQAMIPKGGRMLPQLVCRLVLRCS  (IIa).

In another embodiment of the invention, the SP-B analog is selected fromthose having the following formulae:CLLCRALIKRIQAMIPKGGRMLPQLVCRLVLRCS  (IIb) (SEQ ID NO: 7)CWLCRALIKRIQALIPKGGRLLPQLVCRLVLRCS  (IIc) (SEQ ID NO: 8)CLLCRALIKRIQALIPKGGRLLPQLVCRLVLRCS  (IId) (SEQ ID NO: 9).

In a preferred embodiment, each of the polypeptides (IIa), (IIb), (IIc),and (IId) may be in the form of a disulfide-linked molecule, wherein theintramolecular disulfide linkage is between the two Cys residues inposition 1 and 33 and/or between the two Cys residues in position 4 and27.

The disulfide linked polypeptide (IIa) has been referred to in the artto as oxidized Mini-B (ox Mini-B).

The polypeptide (IIc) is hereinafter referred to as Mini-B(Leu) and itsdisulfide linked form as ox Mini-B(Leu).

The polypeptides of general formulae (I) and (II) may be preparedaccording to synthetic methods or recombinant techniques well known tothe person skilled in the art. An excellent summary of the manytechniques available may be found in J. M. Steward and J. D. Young,“Solid Phase Peptide Synthesis,” W.H. Freeman Co., San Francisco, 1969;and J. Meienhofer, “Hormonal Proteins and Peptides,” Vol. 2, p. 46,Academic Press (New York), 1983, for solid phase peptide synthesis; andin E. Schroder and K. Kubke, “The Peptides,” Vol. 1, Academic Press (NewYork), 1965, for classical solution synthesis.

The polypeptides of the present invention can also be prepared using thesolid-phase synthetic technique initially described by Merrifield, in J.Am. Chem. Soc., 85: 2149-2154 (1963). Other polypeptide synthesistechniques may be found, for example, in M. Bodanszky et al., “PeptideSynthesis: John Wiley & Sons, 2d Ed., (1976) as well as in otherreference works known to those skilled in the art.

Appropriate protective groups for use in such syntheses will be found inthe above texts as well as in J. F. W. McOmie, “Protective Groups inOrganic Chemistry,” Plenum Press, New York, N.Y. (1973).

For example, the polypeptides of general formula (I) may be preparedaccording to the method disclosed in WO 00/47623, while the polypeptidesof general formula (II) may be prepared according to the method reportedin A. J. Waring, et al., J. Peptide Res., 2005, 66, 364-374.

The present invention also provides the pharmaceutically acceptablesalts of the polypeptides of general formulae (I) and (II) and theirblocked N- and/or C-terminus derivatives, e.g., via acetylation andamidation. Pharmaceutically acceptable salts include for example, saltsof hydrochloric acid, acetic acid, and trifluoroacetic acid.

The reconstituted surfactant of the present invention may be prepared bymixing a solution or a suspension of the polypeptides of general formula(I) and (II) and lipids and by subsequently drying the mixture,otherwise they may be prepared by lyophilisation or spray-drying.

Preferably, the polypeptides of general formula (I) and the polypeptidesof general formula (II) are present in the reconstituted surfactants ofthe invention in a fixed amount and quantitative ratio as a fixedcombination.

The proportion of the polypeptides of general formulae (I) and (II)relative to the reconstituted surfactant can vary. Advantageously eachpolypeptide may be present in an amount of 0.5 to 10 wt. % based on thetotal weight of the surfactant (w/w), preferably 1 to 5 wt. %, mostpreferably 1 to 3 wt. %.

In a preferred embodiment, the reconstituted surfactant comprises 1 to3% by weight of the polypeptide (If), and 1 to 3% by weight of thepolypeptide (IIa), preferably in the oxidized form.

In another preferred embodiment, the reconstituted surfactant comprises1 to 3% by weight of the polypeptide (If), and 1 to 3% by weight of thepolypeptide (IIc), preferably in the oxidized form.

Advantageously, the lipid carrier comprises the phospholipids that arecontained in natural pulmonary surfactant preparations, for examplephosphatidylcholines (PC) such as dipalmitoylphosphatidylcholine (DPPC)and palmitoyloleoylphosphatidylcholine (POPC), and phosphatidylglycerols(PG), such as palmitoyloleoylphosphatidylglycerol (POPG) anddipalmitoylposphatidylglycerol (DPPG).

Other phospholipids which can be advantageously used arephosphatidylinositols (PI), phosphatidylethanolamines (PE),phosphatidylserines, and sphingomyelins (SM).

In a particular embodiment, the lipid carrier may comprise furthercomponents, for example neutral lipids such as triacylglycerols, freefatty acids, and/or cholesterol.

Advantageously the reconstituted surfactant according to the presentinvention comprises 90 to 99% by weight of a lipid carrier, preferably92 to 98% by weight, more preferably 94 to 96% by weight, and 1 to 10%by weight of the sum of both peptides, preferably 2 to 8% by weight,more preferably 4 to 6% weight, based on the total weight of the lipidand the polypeptides of formulae (I) and (II).

In one of the embodiments of the present invention, the reconstitutedsurfactant comprises about 96% by weight of a lipid carrier, about 2% byweight of a polypeptide of general formula (I) and about 2% by weight ofa polypeptide of general formula (II).

In a particular embodiment, the lipid carried only consists ofphospholipids more preferably of a mixture of: (1) DPPC; and (2) apalmitoyloleylphospholipid selected from POPG or a mixture thereof withPOPC in weight ratios ranging from 95:5 to 50:50, preferably from 80:20to 60:40.

The weight ratio between DPPC and POPG ranges preferably from 75:25 to65:35, and is more preferably about 68:31. In the case of DPPC:POPG:POPCmixtures, the phospholipids are preferably used in weight ratios ofabout 60:20:20 or about 68:15:16.

In another embodiment, the lipid carrier may consist of DPPC, DPPG, andcholesterol.

In a preferred embodiment of the invention, the reconstituted surfactantcomprises from 1 to 5% by weight of one the polypeptides of generalformula (Ia), from 1 to 5% by weight of one of the polypeptides ofgeneral formula (II) and a mixture of DPPC and POPG in a weight ratio ofabout 68:31.

The administration of the reconstituted surfactant of the invention iscarried out in a manner known to the person skilled in the art,preferably by intratracheal installation (infusion or bolus) or bynebulisation.

The present invention also provides pharmaceutical compositionscomprising the reconstituted surfactant of the invention. Saidcompositions are advantageously administered in the form of a solution,dispersion, suspension, or dry powder. Preferably said compositionscomprise the reconstituted surfactant dissolved or suspended in asuitable solvent or resuspension medium.

Preferably said pharmaceutical compositions are supplied as suspensionin a buffered physiological saline aqueous solution in single-use glassvials. Advantageously, the reconstituted surfactant concentration(expressed as phospholipid content) is in the range of from about 2 toabout 160 mg of surfactant per ml, preferably between 10 and 100 mg/ml,more preferably between 20 and 80 mg/ml.

Said compositions may further comprise electrolytes, such as calcium,magnesium and/or sodium salts, preferably calcium chloride.

The pharmaceutical compositions according to the present invention aresuitable for the prophylaxis and/or treatment of respiratory distresssyndrome (RDS) in prematurely born babies or other diseases related to asurfactant-deficiency or dysfunction including RDS in adults (ARDS),meconium aspiration syndrome (MAS), and bronchopulmonary dysplasia(BPD).

The present reconstituted surfactants may also be useful for theprophylaxis and/or treatment of other respiratory disorders such aspneumonia, bronchitis, COPD (chronic obstructive pulmonary disease),asthma, and cystic fibrosis as well as for the treatment of serousotitis media (glue ear).

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLES Example 1 Synthesis and Purification of the PolypeptidesSP-C33(Leu)³¹ and SP-C33

The polypeptide SP-C33(Leu)³¹ was prepared by standard SPPS (Solid PhasePeptide Synthesis) methods based on Fmoc chemistry and consecutiveTFA-cleavages. In total 186.0 g of crude SP-C33(Leu)³¹ were obtained.The polypeptide was purified by subjecting the material to countercurrent distribution (CCD) using H₂O/n-BuOH/AcOEt/AcOH 4:1:4:1 as abiphasic solvent system. This purification yielded 78.9 g ofSP-C33(Leu)³¹ with a purity of >60%. The final purification was carriedout by preparative HPLC using PLRP-S as the stationary phase in a steelcolumn of 50×300 mm applying a linear gradient of 25% B to 100% B in 75minutes. The mobile phase consisted of buffer A=0.1% TFA in ACN/H₂O 1:4and buffer B=0.1% TFA in IPA. The purified polypeptide was dissolved in90% AcOH and passed through a column packed with Dowex ion exchangeresin (acetate form) to furnish, after lyophilisation, 5.8 g (=5.4%) ofthe final product as the acetate.

The polypeptide SP-C33 was prepared in an analogous manner.

Legend:

ACN Acetonitrile

AcOEt Ethyl acetate

AcOH Acetic acid

Boc t-Butyloxycarbonyl

n-BuOH n-Butanol

Fmoc 9-Fluorenylmethyloxycarbonyl

IPA Isopropyl alcohol

TFA Trifluoroacetic acid

Example 2 Synthesis and Purification of the Polypeptides ox Mini-B(Leu)and ox-Mini-B

The polypeptide ox-Mini-B(Leu) was prepared by standard SPAS (SolidPhase Peptide Synthesis) methods based on Fmoc chemistry and consecutiveTFA-cleavages. The crude polypeptide was purified with preparative HPLCusing a TFA system and isolated by lyophilisation. Air oxidation of thepurified peptide yielded the monocyclic sequence with the disulfide bondbetween Cys¹ and Cys³³. The monocyclic peptide was purified withpreparative HPLC using a TFA system and isolated by lyophilisation. Thesecond disulfide bridge between Cys⁴ and Cys²⁷ was formed using iodine.After oxidation, the product was purified with preparative HPLC using aTFA system and isolated by lyophilisation. 1.12 g (=1.7%) of the finalcompound were isolated with a purity of >89%.

The polypeptide ox Mini-B was prepared in an analogous manner.

Example 3 In Vivo Experiments with a Reconstituted Surfactant Based onOx Mini-B and SP-C33

The surfactant preparations were assayed in premature newborn rabbits,obtained by hysterectomy at the gestational age of 27 days. Theexperiments were performed without applying a positive end expiratorypressure (PEEP). As the SP-C analog, the polypeptide referred to asSP-C33 was used which was prepared according to Example 1. As the analogof the protein SP-B, oxidized Mini-B (ox Mini-B) was used which wasprepared according to Example 2.

The animals were treated at birth with reconstituted surfactantpreparations containing, as lipid carrier, the phospholipid mixtureDPPC:POPG in the ratio 68:31 w/w. The phospholipids were mixed with 2 or4% w/w SPC-33, 2% w/w ox Mini-B, or 2% w/w SPC-33 plus 2% w/w ox Mini-B.Animals receiving the same dose of Curosurf® served as positivecontrols, and non-treated littermates served as negative controls. Allsurfactant preparations were administered at a concentration of 80 mg/mland at a standard dose of 2.5 ml/kg.

The immature newborn rabbits were ventilated in parallel with astandardized sequence of peak insufflation pressures. To open up thelungs, pressure was first set at 35 cmH₂O for 1 minute. After thisrecruitment manoeuvre, pressure was lowered to 25 cmH₂O for 15 minutesand further on to 20 and 15 cm H₂O. Finally, the pressure was raisedagain to 25 cmH₂O for 5 minutes, after which the lungs were ventilatedfor additional 5 minutes with nitrogen and then excised for gas volumemeasurements. Both lung gas volumes and tidal volumes expressed as ml/kgwere measured, and the results, given as median values, are reported inFIGS. 3 and 4, respectively.

From FIG. 3 it can be appreciated that animals treated with thereconstituted surfactant preparation containing 2% w/w ox Mini-B hadlower lung gas volumes than animals that received 2% w/w SP-C33 (about 2ml/kg vs about 4 ml/kg). Addition of 2% w/w ox Mini-B to SP-C33surfactant produced a significantly greater increment in lung gasvolumes than either peptide alone (8 ml/kg vs about 6 ml/kg).

As shown in FIG. 4, a similar trend was observed for the tidal volumesand, after administration of the peptides in combination an improvementcomparable or even slightly better than that achieved afteradministration of Curosurf® was observed. It has also been found thatthe increase of SP-C33 content form 2 to 4% w/w did not increase lunggas volumes indicating that the stabilising effect of the phosholipidfilm in the alveoli at the end of expiration is due to the addition ofox Mini-B. Said result demonstrates that the reconstituted surfactant ofthe invention is able to stabilise the phosholipid film in the alveoliat the end of expiration in a better way than the reconstitutedsurfactants comprising only an analog of the protein SP-C or only ananalog of the protein SP-B. Moreover, the reconstituted surfactantpreparation according to the present invention turned out to improve therespiratory function as expressed by the tidal volumes to an extentcomparable or even slightly better than that achieved afteradministration of a modified natural surfactant.

Where a numerical limit or range is stated herein, the endpoints areincluded. Also, all values and subranges within a numerical limit orrange are specifically included as if explicitly written out.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

All patents and other references mentioned above are incorporated infull herein by this reference, the same as if set forth at length.

The invention claimed is:
 1. A reconstituted surfactant, comprising: (a)a lipid carrier; (b) at least one polypeptide represented by formula(Ic) (SEQ ID NO: 15):IPSSPVHLKRLKLLLLLLLLILLLILGALLΩ_(p)G_(p)L_(p)  (Ic) wherein: Ω is anamino acid residue selected from the group consisting of M, M which isoxidized at the sulfur atom, I, L, and nL; and each p is independently 0or 1, or at least one pharmaceutically acceptable salt thereof, or atleast one blocked N- and/or C-terminus derivative thereof; and (c) atleast one polypeptide represented by formula (II) (SEQ ID NO: 11):C_(f)ΔLCRALIKRIQAΩIPKGGRΩLPQLVCRLVLΦCS_(f)  (II) wherein: Δ is W; each Ωis independently an amino acid residue selected from the groupconsisting of M, I, L, and nL; Φ is R; and f is 1, or at least onepharmaceutically acceptable salt thereof, or at least one blocked N-and/or C-terminus derivative thereof, wherein said polypeptiderepresented by formula (II) is in the form of disulfide linked moleculewith intramolecular disulfide linkages between the two Cys residues inposition 1 and 33 and between the two Cys residues in position 4 and 27,and wherein said lipid carrier comprises a mixture of phospholipids. 2.A reconstituted surfactant according to claim 1, wherein said at leastone polypeptide represented by formula (Ic), pharmaceutically acceptablesalt thereof, or blocked N- and/or C-terminus derivative thereof andsaid at least one polypeptide represented by formula (II),pharmaceutically acceptable salt thereof, or blocked N- and/orC-terminus derivative thereof are each present in an amount of 0.5 to 10wt. %, based on the total weight of the surfactant.
 3. A reconstitutedsurfactant according to claim 1, which comprises at least onepolypeptide represented by formula (IIa) (SEQ ID NO: 6):CWLCRALIKRIQAMIPKGGRMLPQLVCRLVLRCS  (IIa), or at least onepharmaceutically acceptable salt thereof, or at least one blocked N-and/or C-terminus derivative thereof, which is in the form of disulfidelinked molecule with intramolecular disulfide linkages between the twoCys residues in position 1 and 33 and between the two Cys residues inposition 4 and
 27. 4. A reconstituted surfactant according to claim 1,which comprises at least one polypeptide selected from the groupconsisting of: (SEQ ID NO: 1) IPSSPVHLKRLKLLLLLLLLILLLILGALLMGL (Id),(SEQ ID NO: 2) IPSSPVHLKRLKLLLLLLLLILLLILGALLIGL (Ie), (SEQ ID NO: 3)IPSSPVHLKRLKLLLLLLLLILLLILGALLLGL (If), (SEQ ID NO: 4)IPSSPVHLKRLKLLLLLLLLILLLILGALLnLGL (Ig), (SEQ ID NO: 5)IPSSPVHLKRLKLLLLLLLLILLLILGALL (Ih),

a pharmaceutically acceptable salt thereof, or a blocked N- and/orC-terminus derivative thereof.
 5. A reconstituted surfactant accordingto claim 1, which comprises: a polypeptide represented by formula (If)(SEQ ID NO: 3):IPSSPVHLKRLKLLLLLLLLILLLILGALLLGL  (If), a pharmaceutically acceptablesalt thereof, or a blocked N- and/or C-terminus derivative thereof; anda polypeptide represented by formula (IIa) (SEQ ID NO: 6):CWLCRALIKRIQAMIPKGGRMLPQLVCRLVLRCS  (IIa), a pharmaceutically acceptablesalt thereof, or a blocked N- and/or C-terminus derivative thereof,which is in the form of disulfide linked molecule with intramoleculardisulfide linkages between the two Cys residues in position 1 and 33 andbetween the two Cys residues in position 4 and
 27. 6. A reconstitutedsurfactant according to claim 1, which comprises: a polypeptiderepresented by formula (If) (SEQ ID NO: 3):IPSSPVHLKRLKLLLLLLLLILLLILGALLLGL  (If), a pharmaceutically acceptablesalt thereof, or a blocked N- and/or C-terminus derivative thereof; anda polypeptide represented by formula (IIc) (SEQ ID NO: 8):CWLCRALIKRIQALIPKGGRLLPQLVCRLVLRCS  (IIc), a one pharmaceuticallyacceptable salt thereof, or a blocked N- and/or C-terminus derivativethereof, which is in the form of disulfide linked molecule withintramolecular disulfide linkages between the two Cys residues inposition 1 and 33 and between the two Cys residues in position 4 and 27.7. A reconstituted surfactant according to claim 1, wherein said mixtureof phospholipids consists of dipalmitoyl phosphatidylcholine and apalmitoyl oleoyl phospholipid selected from the group consisting ofpalmitoyl oleoyl phosphatidylglycerol, and a mixture of palmitoyl oleoylphosphatidylglycerol with palmitoyl oleoyl phosphatidylcholine in weightratios ranging from 95:5 to 50:50.
 8. A reconstituted surfactantaccording to claim 1, wherein said mixture of phospholipids mixtureconsists of dipalmitoyl phosphatidylcholine and palmitoyl oleoylphosphatidylglycerol in a weight ratio of about 68:31.
 9. Apharmaceutical composition, comprising a reconstituted surfactantaccording to claim
 1. 10. A pharmaceutical composition according toclaim 9, which is in the form of either a solution, a dispersion, asuspension, or a dry powder.
 11. A pharmaceutical composition accordingto claim 10, which is in the form of aqueous suspension.
 12. Apharmaceutical composition according to claim 11, which comprises saidreconstituted surfactant in a concentration of 2 to 160 mg/ml.
 13. Apharmaceutical composition according to claim 12, which comprises saidreconstituted surfactant in a concentration of 20 to 80 mg/ml.
 14. Areconstituted surfactant according to claim 1, which, when administeredto a subject for the treatment or prophylaxis of a disease related to asurfactant deficiency or dysfunction, affords a lung gas volume which isgreater than that afforded by: (1) administration of a reconstitutedsurfactant which comprises (a) said lipid carrier and (b) said at leastone polypeptide represented by formula (Ic) (SEQ ID NO: 15) but no (c)said at least one polypeptide represented by formula (II) (SEQ ID NO:11); and (2) administration of a reconstituted surfactant whichcomprises (a) said lipid carrier and (c) said at least one polypeptiderepresented by formula (II) (SEQ ID NO: 11) but no (b) said at least onepolypeptide represented by formula (Ic) (SEQ ID NO: 15).
 15. A methodfor the treatment and/or prophylaxis of respiratory distress syndrome(RDS) in a prematurely born baby, comprising administering an effectiveamount of a reconstituted surfactant according to claim 1 to saidprematurely born baby.
 16. A method for the treatment or prophylaxis ofa disease related to a surfactant deficiency or dysfunction, comprisingadministering an effective amount of a reconstituted surfactantaccording to claim 1 to a subject in need thereof.
 17. The methodaccording to claim 16, wherein said disease related to a surfactantdeficiency or dysfunction is selected from the group consisting of RDSin an adult, meconium aspiration syndrome, and bronchopulmonarydysplasia.
 18. A method according to claim 15, which affords a lung gasvolume which is greater than that afforded by: (1) administration of areconstituted surfactant which comprises (a) said lipid carrier and (b)said at least one polypeptide represented by formula (Ic) (SEQ ID NO:15) but no (c) said at least one polypeptide represented by formula (II)(SEQ ID NO: 11); and (2) administration of a reconstituted surfactantwhich comprises (a) said lipid carrier and (c) said at least onepolypeptide represented by formula (II) (SEQ ID NO: 11) but no (b) saidat least one polypeptide represented by formula (Ic) (SEQ ID NO: 15).19. A method according to claim 16, which affords a lung gas volumewhich is greater than that afforded by: (1) administration of areconstituted surfactant which comprises (a) said lipid carrier and (b)said at least one polypeptide represented by formula (Ic) (SEQ ID NO:15) but no (c) said at least one polypeptide represented by formula (II)(SEQ ID NO: 11); and (2) administration of a reconstituted surfactantwhich comprises (a) said lipid carrier and (c) said at least onepolypeptide represented by formula (II) (SEQ ID NO: 11) but no (b) saidat least one polypeptide represented by formula (Ic) (SEQ ID NO: 15).20. A method according to claim 17, which affords a lung gas volumewhich is greater than that afforded by: (1) administration of areconstituted surfactant which comprises (a) said lipid carrier and (b)said at least one polypeptide represented by formula (Ic) (SEQ ID NO:15) but no (c) said at least one polypeptide represented by formula (II)(SEQ ID NO: 11); and (2) administration of a reconstituted surfactantwhich comprises (a) said lipid carrier and (c) said at least onepolypeptide represented by formula (II) (SEQ ID NO: 11) but no (b) saidat least one polypeptide represented by formula (Ic) (SEQ ID NO: 15).